3 ms·

So, after some reading and watching... Is this like using balls in space to do computation? It takes no energy to lead them down paths using elastic collisions

So, after some reading and watching... Is this like using balls in space to do computation? It takes no energy to lead them down paths using elastic collisions but it does moving them actively and resetting them to their base position. Then, resetting could also be done by a fully elastic collision causing the ball to go back down its path. But then, it still must take energy to move the switches that send the balls in desired directions, right? But perhaps this is much less. But not 0. I am not a physicist in case this post was not glaringly obvious.

jayd16 8y ago
>But then, it still must take energy to move the switches that send the balls in desired directions, right? If we're talking about theoretical friction-less thought experiments, you could use a lifted barrier, for example, and recover the energy put in when the barrier is lowered.
MayeulC 8y ago
One of the possibilities for adiabatic computing I was interested in some time ago was to use an oscillating power supply. You still lose some energy due to the interconnect resistance, but much less, since you're only sustaining the oscillations (the charges don't get dissipated when returning to the ground, they just move back). Then, it's "only" a matter of deciding which part of the circuit will be powered for the next oscillation, and the switching can be done when vds=0. I haven't had the occasion to think about this as much as I wanted, though, so the above explanation might be incorrect. Hopefully this gives you a better idea of the concept (which there are many ways to approach). So yeah, there are losses (mostly due to circuit resistance), but the "switches" are capacitors, which are just "springs" in the electrical sense. You can get back your energy if done in a clever manner, but we typically just short them to discharge (switch) them :) So, compare the energy required to compact and extend a spring if: * You oscillate with it * You compact it, fully release it, then recompact it. This is a very apt analogy, I think, up to the mathematical level.
vilhelm_s 8y ago
Right, even in the idealized models you need to spend a little bit of energy to write down the input and to read out the output of a computation. But the size of the input/output text is typically very small compared to the number of bit operations done during a computation, so if you can "unscramble" the entire intermediate state back to a low-entropy configuration that will get rid of nearly all the heat. In less idealized models you can't even to do intermediate computations completely losslessly, so those computers will use some energy, but it can approach 0 by working more slowly.

jayd16 8y ago

>But then, it still must take energy to move the switches that send the balls in desired directions, right? If we're talking about theoretical friction-less thought experiments, you could use a lifted barrier, for example, and recover the energy put in when the barrier is lowered.

MayeulC 8y ago

One of the possibilities for adiabatic computing I was interested in some time ago was to use an oscillating power supply. You still lose some energy due to the interconnect resistance, but much less, since you're only sustaining the oscillations (the charges don't get dissipated when returning to the ground, they just move back). Then, it's "only" a matter of deciding which part of the circuit will be powered for the next oscillation, and the switching can be done when vds=0. I haven't had the occasion to think about this as much as I wanted, though, so the above explanation might be incorrect. Hopefully this gives you a better idea of the concept (which there are many ways to approach). So yeah, there are losses (mostly due to circuit resistance), but the "switches" are capacitors, which are just "springs" in the electrical sense. You can get back your energy if done in a clever manner, but we typically just short them to discharge (switch) them :) So, compare the energy required to compact and extend a spring if: * You oscillate with it * You compact it, fully release it, then recompact it. This is a very apt analogy, I think, up to the mathematical level.

vilhelm_s 8y ago

Right, even in the idealized models you need to spend a little bit of energy to write down the input and to read out the output of a computation. But the size of the input/output text is typically very small compared to the number of bit operations done during a computation, so if you can "unscramble" the entire intermediate state back to a low-entropy configuration that will get rid of nearly all the heat. In less idealized models you can't even to do intermediate computations completely losslessly, so those computers will use some energy, but it can approach 0 by working more slowly.